1. Field of the Invention
The present invention is generally related to hard disk drives and disk drive electronic control systems. In particular, the present invention relates to a system for allocating tasks between two actuators serving the same magnetic media within the disk drive system.
2. Description of the Related Art
All disk drives have the common problem of the delay associated with the mechanical latency incurred while the read/write transducer is moved to the correct track on the surface of the disc. One solution for reducing the mechanical latency is the employment of two or more actuators for placing transducers over desired tracks on the disk surface. Two actuators interacting with the same magnetic media allows two different functions to be performed at the same time on the same magnetic media thereby increasing the efficiency of the system. Data management routines have been used to select which actuator should be assigned a specific task so as to minimize the amount of travel the actuator assigned has to travel to start the next task assigned to that actuator. One such data management method is to provide a task queue in which the tasks are placed in the order in which they are received by the disk drive controller. The tasks are then assigned on a first in first out basis to the first actuator to become available for assignment. Another approach is to assign the task within the queue that would require the least amount of travel of the available actuator thereby minimizing the latency time to place the actuator's transducer over the proper track to perform the designated task. The first method, while insuring the priority of the sequence of tasks assigned to the disk drive, still suffers from latency of large movements of the actuator from task to task. The second process, while minimizing the latency time for placing the actuator for the next task may result in a given task not being serviced for a long period of time. The problem of the mechanical latency of the movement of the actuators to the desired track is interrelated with the system's overall efficiency to provide service to a specific task.